Dry powder inhalers have been increasingly used for the delivery of pharmaceuticals to the respiratory tract. In toxicity studies with such materials, one typically adjusts the duration of exposure and aerosol concentration to ensure that test animals receive doses that are appropriate in view of the dosages that one intends to use in subsequent clinical studies.
Most pharmaceuticals that undergo toxicity testing are quite expensive as they are produced on laboratory-scale equipment using procedures that have not yet been optimized. Due to this expense, toxicity testing of new pharmaceuticals typically employs as small a quantity of the pharmaceutical as possible. Thus, there has been a trend away from whole-body animal exposure chambers, which employ relatively large quantities of the test pharmaceutical, to more efficient, second generation devices such as, for example, nose-only chambers. Many of the dry powder aerosol generators that are available, however, have been designed for use with the whole-body exposure chambers and cannot reliably achieve the significantly lower throughput rates of solid material required for the second generation devices.
Consequently, there is a need in the art for devices that can reliably and accurately provide relatively small amounts of solid material for eventual entrainment in an air stream.